Taxol (NSC 125973), a diterpene plant product, is derived from the bark of the western yew Taxus brevifolia. This drug, currently in clinical trials, has exhibited a striking 30 to 40% response rate against advanced cases of ovarian and a number of other cancers. This drug is, however, relatively hydrophobic and not very soluble in aqueous and other biocompatible solvents. Currently, concentrated sterile solutions are made by dissolving this compound into a chremophor. Unfortunately, many patients are allergic and react adversely to this drug formulation. The specific aim of this proposal is to investigate the encapsulation of taxol and its derivatives in liposomes. This investigation should lead to the development of new formulations with improved efficacy and reduced toxicity. Liposomal encapsulation should also lead to improved solubility and stability of taxol and its derivatives while eliminating the allergic and symptomatic reactions of the chremophor solvent.